The invention relates to a high-frequency circuit arrangement, in particular for microwave uses, comprising an insulating substrate provided with a conducting pattern for a reference potential and a semiconductor device.
The invention further relates to a semiconductor device for use in such a high-frequency circuit arrangement.
Such circuit arrangements are used inter alia in circuits for receivers for satellite television.
Such a high-frequency circuit arrangement is described in the article "Low-noise 12 GHz front end designs for direct satellite television reception" in "Philips Technical Review", volume 39, no. 10 (see especially page 267 and FIG. 11). In the preamplifier shown therein, a plurality of transistors (in this case MESFET's) are mounted directly on a conducting pattern, which is formed on an insulating substrate of alumina. The source electrodes of the transistors are connected in an electrically conducting manner to the conductive pattern, which is connected via through-metallized holes in the substrate in an electrically conducting way to the other side of the substrate which is held at a reference potential, in this case ground potential. Such a construction serves to keep parasitic properties (capacitances, and self-inductances) at a minimum or at least to control them between given tolerances.
Various problems arise in the manufacture of such a high-frequency circuit arrangement. For example, the operation of mounting the transistors is often critical and time-consuming. Moreover, it is sometimes necessary to use selected transistors, which involves besides the cost of the additional measurement for this selection also cost as a result of rejection of transistors due to measuring tolerances, damage, transport etc.
However, the main problem, especially at higher frequencies, such as, for example, in use for satellite television, in which frequencies of approximately 12 GHz are utilized, is that the parasitic capacitances and self-inductances must be controlled so that they remain within acceptable limits for the transistor and its surroundings.